模板类函数的"未定义引用"

Question

我正在为一个对象数组编写一个模板类,称之为arrayobjclass,它包含指向其他对象的指针,特别是我实现中的其他数组.数组也作为对象实现,称之为arrayclass.寻找准备好的最小变化.

当我尝试使用以下行测试我的类时,

g++ main.cpp arrayclass.cpp arrayobjclass.cpp -o arrayobj

我收到以下错误:

/tmp/ccEpROXj.o(.text+0x17c): In function `main':
: undefined reference to `arrayobjclass<arrayclass, int>::arrayobjclass(int)'
/tmp/ccEpROXj.o(.text+0x1dc): In function `main':
: undefined reference to `arrayobjclass<arrayclass, int>::addelem(arrayclass*)'
collect2: ld returned 1 exit status

我真的无法理解有什么不对.任何帮助,将不胜感激.如果有帮助,代码的简短相关部分如下.提前致谢!

这就是我的主要内容:

#include "arrayclass.h"
#include "arrayobjclass.h"
#include <iostream>

// 5 arrays of 10 maxsize each
#define MAXSIZE_array 10
#define NUMB_objs 5

using namespace std;

int main () {

    //create a simple array as an arrayclass object
    arrayclass * numbers1 = new arrayclass (MAXSIZE_array);

    //array of objects to hold pointers to simple arrays as created above
    arrayobjclass<arrayclass,int> * myobjs = new arrayobjclass<arrayclass,int> (NUMB_objs);

    //fill up the simple array
    int i;
    for (i=0; i<10; i++) {
        numbers1->addelem(i); 
    }

    //add a pointer to the simple array in my array of objects
    myobjs->addelem(numbers1);    
}

---

//arrayobjclass.h
//declarations of an array of pointers to objects

template <class obj, class key>
class arrayobjclass {

private:
    //obj * arrayptr;
    obj * objarray [];
    int maxsize;
    int totalelem;
public:
    arrayobjclass(int);
    bool addelem(obj *);
};

---

//arrayobjclass.cpp
//implementation of arrayobjclass, array of pointers to objects

#include "arrayobjclass.h"
#include "arrayclass.h"

template <class obj,class key>
arrayobjclass<obj,key>::arrayobjclass (int size){    
    maxsize=size;
    objarray = new obj[maxsize];
    totalelem = 0;
}

template <class obj, class key>
bool arrayobjclass<obj,key>::addelem (obj * newobj) {   
    if (totalelem < maxsize ) {
        objarray[totalelem] = newobj;
        totalelem ++;
        return true;
    }
    return false;
}

---

//arrayclass.h

class arrayclass {

private:
    int * arrayptr;
    int maxsize;
    int totalelem;
public:
    arrayclass(int);
    bool addelem(int);
};

---

//arrayclass.cpp

#include "arrayclass.h"

arrayclass::arrayclass (int size){   
    maxsize=size;
    arrayptr = new int[maxsize];
    totalelem = 0;
}

bool arrayclass::addelem (int addval) {    
    if (totalelem < maxsize ) {
        arrayptr[totalelem] = addval;
        totalelem ++;
        return true;
    }
    return false;
}

Answer 1

您不能将模板声明放在.cpp文件中.模板声明和实现需要在同一个翻译单元中可见.将模板实现放在直接#include的头文件中.

Answer 2

在标题中定义功能模板.编译器需要看到它们.

干杯&hth.,